Although up to 25% of people with myotonic dystrophy report that gastrointestinal symptoms are their most troubling issue, we still understand little about their cause. Myotonic Fellow Dr. Melissa Hinman at the University of Oregon is tackling this issue with Dr. Andy Berglund of the University of Florida using zebrafish models.
Hinman, who received a Case Western University Doctoral Excellence award in 2014 for her work on the NF1 gene, says she was drawn to work on myotonic dystrophy for her postdoctoral fellowship because of the complicated nature of the pathology. “The mechanisms of most genetic diseases that you hear about are a bit boring to me,” she explains, “a mutation in DNA leads to loss or gain of function of some protein, which causes disease phenotypes. RNA-related diseases are much more creative in their mechanisms and it’s a fascinating puzzle try to figure out how they work.”
Focusing in on gastrointestinal (GI) changes in DM, she has hypothesized that inappropriate GI motility in DM causes changes in gut microbiota, which then feed back to impact disease phenotypes. To get at this question, Hinman will characterize whether and how gut motility differs in DM model zebrafish, and use tissue-specific expression of CUG repeats to narrow down the tissues that are responsible for gut phenotypes. She will then use established methods for manipulating zebrafish gut bacteria to determine whether microbiota are necessary for DM related phenotypes, and whether altered bacteria cause DM-related phenotypes in wild type fish.
“It is becoming increasingly clear that human health is influenced not just by our own genome, but also by the genes of the microbes that live on and within us, or the microbiom,” says Hinman. “Deviations from normal microbiota have been shown to contribute to many human disorders such as inflammatory bowel disease, cancer, and obesity. Individuals with diseases that impair gut motility, such as Hirschprung’s disease, often have altered microbiota, which are thought to influence disease severity. Since gut motility is also affected in DM, we are investigating whether there are associated changes in microbiota and how these changes might influence disease symptoms.”
After several months of prep work she is finally ready to start characterizing several new stable models of DM in zebrafish, and is looking forward to seeing what light they may be able to shed on gut phenotypes. Although mentor Andy Berglund’s focus on myotonic dystrophy matched her interests well, Hinman says that it’s an added bonus that the University of Oregon is the birthplace of the zebrafish as a model organism and home to many zebrafish experts, including her co-mentor Karen Guillemin (because Berglund has moved to the University of Florida, Hinman is finishing her project in Guillemin’s laboratory). In the future she would like to delve deeper into the molecular mechanisms behind myotonic dystrophy and speculates that zebrafish would be an ideal model for this goal, as well as for screening therapeutic compounds.
Hinman will be giving a talk about her work at the Myotonic Annual Conference in Washington, DC, on September 19th. She says she is most looking forward to meeting people who are living with the disease, saying “I never got the opportunity to meet anyone with NF1 (the disease that I studied in graduate school), and as a result I felt like I didn’t fully understand the disease.” Dr. Hinman’s talk will be recorded and available to view on the Myotonic website by the end of September.